It's not China that would be (re)purchasing it, it's almost certainly a private entity. Seizing vessels and levying fines are fully within the normal activities

It's not China that would be (re)purchasing it, it's almost certainly a private entity. Seizing vessels and levying fines are fully within the normal activities and responsibilities of governments, and civil actions plus maybe a few relatively minor criminal charges are much less likely to draw public condemnation and retaliation from the Chinese government.